CVE-2026-1801

Publication date 3 February 2026

Last updated 15 September 2026

Ubuntu priority

Cvss 3 Severity Score

Description

A flaw was found in libsoup, an HTTP client/server library. This HTTP Request Smuggling vulnerability arises from non-RFC-compliant parsing in the soup_filter_input_stream_read_line() logic, where libsoup accepts malformed chunk headers, such as lone line feed (LF) characters instead of the required carriage return and line feed (CRLF). A remote attacker can exploit this without authentication or user interaction by sending specially crafted chunked requests. This allows libsoup to parse and process multiple HTTP requests from a single network message, potentially leading to information disclosure.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
libsoup2.4	26.04 LTS resolute	Vulnerable
	25.10 questing	Ignored end of life, was needs-triage
	24.04 LTS noble	Vulnerable
	22.04 LTS jammy	Vulnerable
	20.04 LTS focal	Vulnerable
	18.04 LTS bionic	Vulnerable
	16.04 LTS xenial	Needs evaluation
libsoup3	26.04 LTS resolute	Not affected
	25.10 questing	Ignored end of life, was needs-triage
	24.04 LTS noble	Vulnerable
	22.04 LTS jammy	Vulnerable

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
libsoup2.4	Upstream: b9a1c06
libsoup3	Upstream: b9a1c06

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.3 · Medium

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	Low
Availability impact	None

Scores

Parameter	Value
Base score	5.3 · Medium
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N